Hygro-thermostat



i '14, 1931- c. c. BRADBURY 1,814,585

HYGRO THERMOSTAT Filed Oct. 6, 1920 Patented July 14, 1931 PATENT orFICE CLIFFORD C. BRADBURY, 01 OAK PARK, ILLINOIS HYGRO-THERMOSTAT i 1Application filed October 6, 1920. Serial No. 415,130.

My invention relates to a combined hygrostat and thermostat; moreconveniently designated a hygro-thermostat.

While the invention is capable of wide adaptations, it is particularlydesigned for use in connection with the regulation of the 5 should be,for similar comfort, 1 F. de-

crease of temperature, and likewise for substantially" 10% decrease inhumidity, there should be, for similar comfort, 1 F. increase oftemperature. My invention, thereperature regulation which varies withthe humidity of the atmosphere, so as to pro- 'duce at all differentdegrees of humidity substantially the same degree of comfort.

The invention will be better understood from the following descriptionby reference to the accompanying drawings, wherein.

Figure 1 is a View partly in section, and partly in elevation of theinstrument of my invention, and

Figure 2 is a sectional detail taken on line 2-2 of Figure 1, looking inthe direction indicated by the arrows.

Referring to the drawings, the reference numeral 5 designates a panelboard which may be secured in any suitable manner on the wall of a room,and'on which is mounted a bracket 6, to which is secured by means ofrivets the thermostat indicated generally by the reference numeral 7.This thermostat comprises the metal strips 8 and 9, having differentcoeflicients of expansion, the strips 8 being preferably of molybdenum,and the strip 9 of aluminum. These strips are secured by means of rivets10-10 to an intermediate strip of hard rubber or any other suitable heatinsulating material 11. It will be seen that the heads of the rivetswhich secure one metal strip to the intermediate heat insulating stripproject into the container 15 to refill the same. fore, is for thepurpose of causing a temholes provided in the other metal strip, to pprevent the conduction. of heat from one metal strip to the other. Thefree end of the metal strip 8 is disposed between the two contacts 12and 13, and is 'arranged to engage one of these contacts when the pairof strips is deiiexed, first in one direction and then in the other,depending upon the temperature of the room. The contacts 12 and 13 areadjustably mounted in the brack-' et 14, and are suitablyinsulatedtherefrom. At 15 is indicated a removable water container theback of which is provided with the elongated slots 16-16, through whichthe screws 17 on the panel board 5 project. The lower ends of theelongated slots 16 are enlarged to permit passage of the heads of thescrews 17 thercthrough when reniovin A wic 18 extends from the watercontainer and lies in contact with the strip 9, which has the greatercoefficient of expansion of the two metal strips. The strip 9, as shownmost clearly in Figure 2, is provided with the inwardly bent lugs 19,which serve to hold the wick 18 into intimate contact with the strip 9.By this construction, it is possible to move the wick 18 along the stripso as to contact different lengths of it, depending upon the degree inchange of temperature desired for different degrees of atmospherichumidity. Secured upon the bracket 6 is an electrical contact 20, withwhich is connected the conductor 21. Conductors 22 and 23 areelectrically connected with the adjustable contacts 12 and 13respectively. The three conductors 21, 22 and 23 form a three-waycircuit for a furnace or heatercontrollerof any one of the well knowntypes, which may alternately be put into and out of operation, to effectregulation of the room temperature.

The operation of the device is as follows:

Let us assume that the heater controller has been operated so that thefurnace is caused to produce a rise in temperature of the room. Themetal strips 8 and,9 expand due to this rise in temperature. The strip9, expanding at a greater rate than the strip 8, causes a flexure of thepair of elements to the left (see Figure 1) whereby an electricalcircuit is completed through the conductor: 22, contact 12, metal strip8, bracket 6, contact 20, conductor 21, to the furnace controller. Thecontroller may be v of any convenient form and is preferably of thattype which, when the circuit is initially closed therethrough, is causedto operate for a predetermined interval to cause a certain definiteoperation of the controller. After the controller has thus been causedto operate, to regulate the draft of the furnabe, for example, thetemperature of the room drops, thereby causing the metal strips 8 and 9to contract. The strip 9 contracting at a faster rate than the strip 8,causes a flexure of the pair of thermostatic elements to the right (seeFigure 1) thereby breaking the circuit above described. If the roomtemperature falls low enough, the strips contract to such an extent thatthe flexure is suificient to cause the free end of the strip 8 to engagethe contact 13. A.

new circuit is thus completed, through the conductor 23, contact 13,metal strip 8, bracket 6, contact 20, conductor 21, to the furnace orheater controller. The controller is thereby caused to operatesubstantially as before to open the draft, for example, whereby to causea renewed opera tion of the furnace to produce a rise in temperature ofthe room. It will be understood that the device may be so adjusted as toclose the electrical connection with the controller to cause operationof the furnace at a temperature of say F., in an atmosphere of averagehumidity. In the event that. the atmosphere is less saturated theevaporation of the moisture in the wick Wlll be more rapid, so that themetal strip 9, with which the wick contacts, on account of theinsulating strip 11, will be maintained a greater degree cooler than thestrip 8, which, of course, is not wet by the wick, whereforethedeflection of the thermostatic pair to a given position will requirea greater degree of heat than under normal conditions of humidity. inthe event that the atmosphere contains more moisture than that for whichthe thermostat has been adjusted, the rapidity with which the waterevaporates from the wick will be less. The strip 9, which contacts withthe wick, itil'l therefore remain more nearly at the same temperature asthe surrounding atmospli'ere and the deflection of the thermostatic pairto a given position will occur therefore at a lower ten'iperature. Thecontacts 12 and 13 are conveniently adjusted so that the contact 13engages the strip 8 when the temperature of the room falls below apredetermined amount, and so that the contact 12 engages the strip 8when the temperature rises above a predetermined amount. The

wick l8 is movable up and down on the strip 9 between the lugs 1919, tovary the length of contact depending upon the degree in change oftemperature desired, for different degrees of atmospheric humidity. Bythe use of this device, a temperature regulation is secured, whichvaries with the humidity of the atmosphere, so as to produce practicallythe same degree of comfort at all different degrees of humidity.

Having thus described my invention, what I claim as new and desire tosecure by United States Letters Patents is:

1. The combination in a device of the class described of a thermostatcomprising a pair of elements adapted to deflex subject to a rise andvfall in temperature of the atmosphere, and a saturated hygro-staticwick, contacting with the element of said pair having the greatercoefficient of expansion, the moisture of said wick being subject toevaporation depending upon the relative humidity of the atmosphere, saidwick being adjustable lengthwise of said thermostatic element whereby toalter the degree in change of temperature obtained for different degreesof atmospheric humidity.

2. The combination in a device of the class described of a thermostatcomprising a pair of elements adapted to deflex subject to a rise andfall in temperature of the atmosphere, and a saturated hygro-staticwick, contacting with the element of said pair having the greatercoeflicient of expansion, the moistureof said wick being subject toevaporation depending upon the relative humidity of the atmosphere.

3. The combination in a device of the class described of a thermostatcomprising a pair of elements adapted to deflex subject to a rise andfall in temperature of the atmosphere, a saturated hygro statiewick,

contacting with the element of said pair having the greater cceflicientof expansion, the moisture of said wick being subject to evaporationdepending upon the relative humidity of the atmosphere, and alternateelectrical contacts closed by the fiexure of said thermostatic pair tocause the operation of a heater controller. whereby'to effect aregulation of the temperature of a room.

4. A hygro-thermostat for heat control cgnnprisinga pair of elements f.i;- .diflering temperature coeflicients of expansion, each of saidelements being comparatively fiat and lying parallel to one another,heat insulating material lying between said elements, the two elementsand the heat insulating material being firmly attached together to forma flexing unit, and means to moisten one of said elements so that therate of evaporation from said element will influence the temperature atwhich the unit is flexed to a predetermined position.

5. A hygro-thermostat comprising a pair of elements of difi'eringcoeflicients of eitpansion, and a member interposed between saidelements having a poor heat conductivity, and means to moisten one ofsaid elements to influence the deflection of the pair according to thehumidity of the atmosphere.

6. In a hygro-thermostat for temperature regulation, means affected bytemperature changes and means affected by humidity changes, said meansbeing united into one instrument and conjointly controlling a movablemember whereby said member will respond differently to changes intemperature for different degrees of atmospheric humidity forautomatically altering the temperature responsive to changes inhumidity.

7. A member movable responsive to changes in room temperature, saidmember being also movable responsive to changes in atmospheric humidity,controlling means for said member said means being so pro-. portionedthat the movable member will be moved from a predetermined positioneither by a rise in temperature or an increase in atmospheric humidity,but will remain in an unchanged position upon a drop in temperature anda simultaneous predetermined increase in atmospheric humidity, wherebythe movement of said member may be utilized for regulating atmospherictemperature to correspond with changes in atmospheric humidity. I

In mechanism for automatically regulating the temperature of a room, acontrol circuit for increasing or decreasing the heat supply for saidroom, a circuit changer operably responsive to temperature changes,means responsive to changes in atmospheric humidity for modifying theoperation of said circuit changer, said means and circuit changer beingso proportioned and co related that the said circuit changer will bemodified from a predetermined state, either by an increase inatmospheric humidity or by a rise in temperature, but Will remain in itsunmodified predetermined state upon an increase in atmospheric humidityaccompanied by a predetermined fall in temperature or, conversely, thatsaid circuit changer Will be modified from said predetermined stateeither by a decrease in' atmospheric humidity or by a fall intemperature but will remain in its unmodified predetermined state upon adecrease in atmospheric humidity accompanied by a predetermined rise intemperature, the degree of change in temperature brought about by saidmchanism being such as to result in a constant feeling of comfort to thehuman body through variations in atmospheric humidity in said room.

9. In mechanism for automatically regulating the temperature of a room,a control circuit for increasing and decreasing the heat supply for saidroom, a circuit changer therefor operative in response to changes oftemperature to maintain substantially constant temperature of the air insaid room when the humidity of the air in said room is constant, andmeans responsive to changes in humidity for automatically modifying theactuation of the circuit changer so that a lower temperature of air ismaintained in said room for higher humidity of the air in said room anda higher temperature of air is maintained in said room for a lowerhumidity of air in said room, the temperature operated circuit changerand the means responsive to changes in humidity being so proportionedand co-related that ten per cent increase in humidity producesapproximately the same effect upon the circuit changer as is produced by1 F. increase in temperature and that ten per cent decrease in humidityproduces approximately the same effect upon the circuit changer as isproduced by 1 F. decrease in temperature. I11 witness whereof, Ihereunto subscribe my name this 1st day of October, 1920.

CLIFFORD C. BRADBURY.

